/*******************************************************************************
 * Copyright (c) 2015, 2016 EclipseSource.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/

/**
 * ATTRIBUTION NOTICE
 * ==================
 * MinimalJson is a fast and minimal JSON parser and writer for Java. It's not an object mapper, but a bare-bones library that aims at being:
 * - minimal: no dependencies, single package with just a few classes, small download size (< 35kB)
 * - fast: high performance comparable with other state-of-the-art parsers (see below)
 * - lightweight: object representation with minimal memory footprint (e.g. no HashMaps)
 * - simple: reading, writing and modifying JSON with minimal code (short names, fluent style)
 *
 * Minimal JSON can be found at https://github.com/ralfstx/minimal-json.
 *
 * Minimal JSON is licensed under the MIT License, see https://github.com/ralfstx/minimal-json/blob/master/LICENSE
 *
 */
package com.espertech.esper.common.client.json.minimaljson;

import java.io.*;


/**
 * Represents a JSON value. This can be a JSON <strong>object</strong>, an <strong> array</strong>,
 * a <strong>number</strong>, a <strong>string</strong>, or one of the literals
 * <strong>true</strong>, <strong>false</strong>, and <strong>null</strong>.
 * <p>
 * The literals <strong>true</strong>, <strong>false</strong>, and <strong>null</strong> are
 * represented by the constants {@link Json#TRUE}, {@link Json#FALSE}, and {@link Json#NULL}.
 * </p>
 * <p>
 * JSON <strong>objects</strong> and <strong>arrays</strong> are represented by the subtypes
 * {@link JsonObject} and {@link JsonArray}. Instances of these types can be created using the
 * public constructors of these classes.
 * </p>
 * <p>
 * Instances that represent JSON <strong>numbers</strong>, <strong>strings</strong> and
 * <strong>boolean</strong> values can be created using the static factory methods
 * {@link Json#value(String)}, {@link Json#value(long)}, {@link Json#value(double)}, etc.
 * </p>
 * <p>
 * In order to find out whether an instance of this class is of a certain type, the methods
 * {@link #isObject()}, {@link #isArray()}, {@link #isString()}, {@link #isNumber()} etc. can be
 * used.
 * </p>
 * <p>
 * If the type of a JSON value is known, the methods {@link #asObject()}, {@link #asArray()},
 * {@link #asString()}, {@link #asInt()}, etc. can be used to get this value directly in the
 * appropriate target type.
 * </p>
 * <p>
 * This class is <strong>not supposed to be extended</strong> by clients.
 * </p>
 */
@SuppressWarnings("serial") // use default serial UID
public abstract class JsonValue implements Serializable {

    /**
     * Represents the JSON literal <code>true</code>.
     *
     * @deprecated Use <code>Json.TRUE</code> instead
     */
    @Deprecated
    public static final JsonValue TRUE = new JsonLiteral("true");

    /**
     * Represents the JSON literal <code>false</code>.
     *
     * @deprecated Use <code>Json.FALSE</code> instead
     */
    @Deprecated
    public static final JsonValue FALSE = new JsonLiteral("false");

    /**
     * Represents the JSON literal <code>null</code>.
     *
     * @deprecated Use <code>Json.NULL</code> instead
     */
    @Deprecated
    public static final JsonValue NULL = new JsonLiteral("null");

    JsonValue() {
        // prevent subclasses outside of this package
    }

    /**
     * Reads a JSON value from the given reader.
     * <p>
     * Characters are read in chunks and buffered internally, therefore wrapping an existing reader in
     * an additional <code>BufferedReader</code> does <strong>not</strong> improve reading
     * performance.
     * </p>
     *
     * @param reader the reader to read the JSON value from
     * @return the JSON value that has been read
     * @throws IOException    if an I/O error occurs in the reader
     * @throws ParseException if the input is not valid JSON
     * @deprecated Use {@link Json#parse(Reader)} instead
     */
    @Deprecated
    public static JsonValue readFrom(Reader reader) throws IOException {
        return Json.parse(reader);
    }

    /**
     * Reads a JSON value from the given string.
     *
     * @param text the string that contains the JSON value
     * @return the JSON value that has been read
     * @throws ParseException if the input is not valid JSON
     * @deprecated Use {@link Json#parse(String)} instead
     */
    @Deprecated
    public static JsonValue readFrom(String text) {
        return Json.parse(text);
    }

    /**
     * Returns a JsonValue instance that represents the given <code>int</code> value.
     *
     * @param value the value to get a JSON representation for
     * @return a JSON value that represents the given value
     * @deprecated Use <code>Json.value()</code> instead
     */
    @Deprecated
    public static JsonValue valueOf(int value) {
        return Json.value(value);
    }

    /**
     * Returns a JsonValue instance that represents the given <code>long</code> value.
     *
     * @param value the value to get a JSON representation for
     * @return a JSON value that represents the given value
     * @deprecated Use <code>Json.value()</code> instead
     */
    @Deprecated
    public static JsonValue valueOf(long value) {
        return Json.value(value);
    }

    /**
     * Returns a JsonValue instance that represents the given <code>float</code> value.
     *
     * @param value the value to get a JSON representation for
     * @return a JSON value that represents the given value
     * @deprecated Use <code>Json.value()</code> instead
     */
    @Deprecated
    public static JsonValue valueOf(float value) {
        return Json.value(value);
    }

    /**
     * Returns a JsonValue instance that represents the given <code>double</code> value.
     *
     * @param value the value to get a JSON representation for
     * @return a JSON value that represents the given value
     * @deprecated Use <code>Json.value()</code> instead
     */
    @Deprecated
    public static JsonValue valueOf(double value) {
        return Json.value(value);
    }

    /**
     * Returns a JsonValue instance that represents the given string.
     *
     * @param string the string to get a JSON representation for
     * @return a JSON value that represents the given string
     * @deprecated Use <code>Json.value()</code> instead
     */
    @Deprecated
    public static JsonValue valueOf(String string) {
        return Json.value(string);
    }

    /**
     * Returns a JsonValue instance that represents the given <code>boolean</code> value.
     *
     * @param value the value to get a JSON representation for
     * @return a JSON value that represents the given value
     * @deprecated Use <code>Json.value()</code> instead
     */
    @Deprecated
    public static JsonValue valueOf(boolean value) {
        return Json.value(value);
    }

    /**
     * Detects whether this value represents a JSON object. If this is the case, this value is an
     * instance of {@link JsonObject}.
     *
     * @return <code>true</code> if this value is an instance of JsonObject
     */
    public boolean isObject() {
        return false;
    }

    /**
     * Detects whether this value represents a JSON array. If this is the case, this value is an
     * instance of {@link JsonArray}.
     *
     * @return <code>true</code> if this value is an instance of JsonArray
     */
    public boolean isArray() {
        return false;
    }

    /**
     * Detects whether this value represents a JSON number.
     *
     * @return <code>true</code> if this value represents a JSON number
     */
    public boolean isNumber() {
        return false;
    }

    /**
     * Detects whether this value represents a JSON string.
     *
     * @return <code>true</code> if this value represents a JSON string
     */
    public boolean isString() {
        return false;
    }

    /**
     * Detects whether this value represents a boolean value.
     *
     * @return <code>true</code> if this value represents either the JSON literal <code>true</code> or
     * <code>false</code>
     */
    public boolean isBoolean() {
        return false;
    }

    /**
     * Detects whether this value represents the JSON literal <code>true</code>.
     *
     * @return <code>true</code> if this value represents the JSON literal <code>true</code>
     */
    public boolean isTrue() {
        return false;
    }

    /**
     * Detects whether this value represents the JSON literal <code>false</code>.
     *
     * @return <code>true</code> if this value represents the JSON literal <code>false</code>
     */
    public boolean isFalse() {
        return false;
    }

    /**
     * Detects whether this value represents the JSON literal <code>null</code>.
     *
     * @return <code>true</code> if this value represents the JSON literal <code>null</code>
     */
    public boolean isNull() {
        return false;
    }

    /**
     * Returns this JSON value as {@link JsonObject}, assuming that this value represents a JSON
     * object. If this is not the case, an exception is thrown.
     *
     * @return a JSONObject for this value
     * @throws UnsupportedOperationException if this value is not a JSON object
     */
    public JsonObject asObject() {
        throw new UnsupportedOperationException("Not an object: " + toString());
    }

    /**
     * Returns this JSON value as {@link JsonArray}, assuming that this value represents a JSON array.
     * If this is not the case, an exception is thrown.
     *
     * @return a JSONArray for this value
     * @throws UnsupportedOperationException if this value is not a JSON array
     */
    public JsonArray asArray() {
        throw new UnsupportedOperationException("Not an array: " + toString());
    }

    /**
     * Returns this JSON value as an <code>int</code> value, assuming that this value represents a
     * JSON number that can be interpreted as Java <code>int</code>. If this is not the case, an
     * exception is thrown.
     * <p>
     * To be interpreted as Java <code>int</code>, the JSON number must neither contain an exponent
     * nor a fraction part. Moreover, the number must be in the <code>Integer</code> range.
     * </p>
     *
     * @return this value as <code>int</code>
     * @throws UnsupportedOperationException if this value is not a JSON number
     * @throws NumberFormatException         if this JSON number can not be interpreted as <code>int</code> value
     */
    public int asInt() {
        throw new UnsupportedOperationException("Not a number: " + toString());
    }

    /**
     * Returns this JSON value as a <code>long</code> value, assuming that this value represents a
     * JSON number that can be interpreted as Java <code>long</code>. If this is not the case, an
     * exception is thrown.
     * <p>
     * To be interpreted as Java <code>long</code>, the JSON number must neither contain an exponent
     * nor a fraction part. Moreover, the number must be in the <code>Long</code> range.
     * </p>
     *
     * @return this value as <code>long</code>
     * @throws UnsupportedOperationException if this value is not a JSON number
     * @throws NumberFormatException         if this JSON number can not be interpreted as <code>long</code> value
     */
    public long asLong() {
        throw new UnsupportedOperationException("Not a number: " + toString());
    }

    /**
     * Returns this JSON value as a <code>float</code> value, assuming that this value represents a
     * JSON number. If this is not the case, an exception is thrown.
     * <p>
     * If the JSON number is out of the <code>Float</code> range, {@link Float#POSITIVE_INFINITY} or
     * {@link Float#NEGATIVE_INFINITY} is returned.
     * </p>
     *
     * @return this value as <code>float</code>
     * @throws UnsupportedOperationException if this value is not a JSON number
     */
    public float asFloat() {
        throw new UnsupportedOperationException("Not a number: " + toString());
    }

    /**
     * Returns this JSON value as a <code>double</code> value, assuming that this value represents a
     * JSON number. If this is not the case, an exception is thrown.
     * <p>
     * If the JSON number is out of the <code>Double</code> range, {@link Double#POSITIVE_INFINITY} or
     * {@link Double#NEGATIVE_INFINITY} is returned.
     * </p>
     *
     * @return this value as <code>double</code>
     * @throws UnsupportedOperationException if this value is not a JSON number
     */
    public double asDouble() {
        throw new UnsupportedOperationException("Not a number: " + toString());
    }

    /**
     * Returns this JSON value as String, assuming that this value represents a JSON string. If this
     * is not the case, an exception is thrown.
     *
     * @return the string represented by this value
     * @throws UnsupportedOperationException if this value is not a JSON string
     */
    public String asString() {
        throw new UnsupportedOperationException("Not a string: " + toString());
    }

    /**
     * Returns this JSON value as a <code>boolean</code> value, assuming that this value is either
     * <code>true</code> or <code>false</code>. If this is not the case, an exception is thrown.
     *
     * @return this value as <code>boolean</code>
     * @throws UnsupportedOperationException if this value is neither <code>true</code> or <code>false</code>
     */
    public boolean asBoolean() {
        throw new UnsupportedOperationException("Not a boolean: " + toString());
    }

    /**
     * Writes the JSON representation of this value to the given writer in its minimal form, without
     * any additional whitespace.
     * <p>
     * Writing performance can be improved by using a {@link java.io.BufferedWriter BufferedWriter}.
     * </p>
     *
     * @param writer the writer to write this value to
     * @throws IOException if an I/O error occurs in the writer
     */
    public void writeTo(Writer writer) throws IOException {
        writeTo(writer, WriterConfig.MINIMAL);
    }

    /**
     * Writes the JSON representation of this value to the given writer using the given formatting.
     * <p>
     * Writing performance can be improved by using a {@link java.io.BufferedWriter BufferedWriter}.
     * </p>
     *
     * @param writer the writer to write this value to
     * @param config a configuration that controls the formatting or <code>null</code> for the minimal form
     * @throws IOException if an I/O error occurs in the writer
     */
    public void writeTo(Writer writer, WriterConfig config) throws IOException {
        if (writer == null) {
            throw new NullPointerException("writer is null");
        }
        if (config == null) {
            throw new NullPointerException("config is null");
        }
        WritingBuffer buffer = new WritingBuffer(writer, 128);
        write(config.createWriter(buffer));
        buffer.flush();
    }

    /**
     * Returns the JSON string for this value in its minimal form, without any additional whitespace.
     * The result is guaranteed to be a valid input for the method {@link Json#parse(String)} and to
     * create a value that is <em>equal</em> to this object.
     *
     * @return a JSON string that represents this value
     */
    @Override
    public String toString() {
        return toString(WriterConfig.MINIMAL);
    }

    /**
     * Returns the JSON string for this value using the given formatting.
     *
     * @param config a configuration that controls the formatting or <code>null</code> for the minimal form
     * @return a JSON string that represents this value
     */
    public String toString(WriterConfig config) {
        StringWriter writer = new StringWriter();
        try {
            writeTo(writer, config);
        } catch (IOException exception) {
            // StringWriter does not throw IOExceptions
            throw new RuntimeException(exception);
        }
        return writer.toString();
    }

    /**
     * Indicates whether some other object is "equal to" this one according to the contract specified
     * in {@link Object#equals(Object)}.
     * <p>
     * Two JsonValues are considered equal if and only if they represent the same JSON text. As a
     * consequence, two given JsonObjects may be different even though they contain the same set of
     * names with the same values, but in a different order.
     * </p>
     *
     * @param object the reference object with which to compare
     * @return true if this object is the same as the object argument; false otherwise
     */
    @Override
    public boolean equals(Object object) {
        return super.equals(object);
    }

    @Override
    public int hashCode() {
        return super.hashCode();
    }

    abstract void write(JsonWriter writer) throws IOException;

}
